Hinges are quite often used in various electric and electronic apparatus to connect two members of the apparatus, so that the two members are pivotally turnable about the hinges relative to one another. For example, a notebook computer uses hinges to pivotally connect a liquid crystal display (LCD) to a computer case, so that a user may pivotally lift and close the LCD from and onto the computer case. There are still many other devices, such as mobile phones, personal digital assistants (PDAs), global positioning systems (GPSs), and many testing instruments, that use hinges thereon.
A conventional hinge mainly includes one or two leaves, each of which is formed at one lateral edge with a barrel, through which a pintle is extended. When the pintle is turned, an outer wall surface of the pintle is in frictional contact with an inner wall surface of the barrels, so as to provide a fixed moment of force required by the apparatus using the hinge. To enable the device using the hinge to always have constant friction moment when being lifted or closed, a forward-extending barrel and a reversely-extending barrel are normally provided at one lateral edge of the leaf, so that the two barrels enclose the pintle in two opposite directions.
There are various types of hinges of prior art developed to meet different demands for hinges. For example, U.S. Pat. No. 6,671,929 discloses a hinge for a notebook computer composed of a pintle, a resilient sleeve, and two barrels. Each of the two barrels is formed at one side of a leaf, and the pintle is extended through the two barrels to thereby connect to the two leaves. U.S. Pat. No. 6,820,307 discloses an elastic hinge for a notebook computer compose of a pintle and two barrels. Each of the two barrels is formed at one side of a leaf, and the pintle is extended through the two barrels to thereby connect to the two leaves. U.S. Pat. No. 6,470,532 discloses a hinge for notebook computer including a band portion having a cylinder portion formed at one edge thereof, a lid portion having an opening formed thereon, and a hinge pin extended through the cylinder portion on the band portion and the opening on the lid portion. U.S. Pat. No. 6,711,782 discloses a duplex opposite friction hinge. U.S. Pat. No. 6,321,416 discloses a hinge for a notebook computer composed of a leaf having a C-shaped sleeve formed at an edge thereof and a pintle pivotally received in the C-shaped sleeve of the leaf.
There are some problems existed in the hinges of prior art. For example, most of the conventional hinge structures include at least one leaf, one side of which is curved approximately by 360 degrees to form at least one barrel. It requires highly accurate technique and accordingly, highly precision machines to mechanically form the barrel. Once the barrel is formed, it is impossible to adjust a compression force applied by the barrel against the pintle. When the hinge has been used over a long time, the compression force applied by the barrel against the pintle would become reduced due to wearing off of material under frequent frictional contact of the barrel with the pintle.
There is also problem in the association of the pintle with the barrel. Since the formed barrel has a considerably high mechanical deformation resistance, the pintle is conventionally fitted in the barrel by aligning the pintle with the barrel and then driving the pintle into the barrel with a suitable tool. By doing this, a lot of time and labors are required while there is a high defect rate of the final products. In case of any minor error in the assembling operation, both the pintle and the leaf are subjected to damage, and the inaccurately assembled hinge has to be wasted.